AMBIENT ALERT
App using the phone's microphone to listen to changes in the sound, incase of any loud sounds (customizable), the app will play an alert to warn you of possible danger.

MUSIC
With the streaming running/walking music you don't have to worry about ever looking for music again. The app will stream just the right kind of music to keep you pumped on your run.
(Don't like the streaming music, you can always use your iPhone Music player with justRun as well)

GPS
Full tracking of your run and details on each data point like MPH, calories, and distance.
For treadmill runs the app will use the iPhone accelerometer to estimate your distance.